DE2537045A1 - TRANSPARENT MELT ADHESIVE - Google Patents

Description

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Applicant: KORES HOLDING ZUG AG

Baarerstrasse CH-6300 Zug / Switzerland

TRANSPARENT MELT ADHESIVE

709808/0899

2 5 3 7 O A

The present invention relates to a transparent hot melt adhesive with improved resistance to aging.

Pressure-sensitive adhesives are mostly used as solutions or dispersions in organic solvents on a suitable one Carrier applied depending on the intended use.

Lately, however, there has been a trend towards the use of organic To limit solvents as far as possible for reasons of environmental hygiene or to refrain from using them, since processing causes damage to health. Another problem especially in the production of adhesive tapes, which have a carrier based on plastic, is seen in that by electrostatic charging of the plastic film there is a risk of sparks. This can cause the solvent vapors to self-ignite.

When applying the solution are also in the production speed Limits set

There has therefore recently been a move towards applying pressure-sensitive adhesives from the melt. However, there were a number of them of problems that had to be accepted depending on the intended use.

A striking disadvantageous feature is the low oxidation and temperature resistance of the so-called hotmelt pressure-sensitive adhesives, since the mastifying and application of the adhesive has to go to relatively high temperatures. Although it There are separate application units for applying the hot melt adhesive, but the melt viscosity of the adhesive must not be too high lie high. In order to lower the melt viscosity, the degree of polymerization of the adhesive component has to be relatively low held and added plasticizer. As a result, however, the stability values deteriorated to the point that permanent Bondings could not be achieved when the bonded objects were exposed to permanent stress.

709808/0998

Accordingly, the hot melt pressure sensitive adhesives were only for specific uses suitable.

A particular disadvantage of hotmelt PSAs has been felt to be their low resistance to oxidation and aging, see above that they are used for self-adhesive tapes whose backing is made of transparent material, such as cellophane, polyvinyl chloride or polyvinyl acetate are manufactured, are not usable. The insufficient resistance to oxidation leads to the known disadvantageous yellowing of the adhesive tapes. In connection with this, however, it deteriorates also the adhesiveness, so that the adhesive tapes peel off by themselves from the base after some time.

It has already been proposed to use pressure-sensitive adhesives based on resinous, rubber-like block copolymers of styrene and butadiene or styrene and isoprene with additions of modified or unmodified rosin or rosin ester, coumarone-indene resins, Polyterpene resins, aliphatic diene-olefin hydrocarbon resins or polystyrene resins and copolymers of ethylene-vinyl acetate to manufacture. However, the problem of the UV and oxidation resistance of the hotmelt PSA could not be solved because, in particular, the stability of the copolymer of ethylene and vinyl acetate is not satisfactory Extent could also be achieved by adding stabilizers.

The same applies to hotmelt pressure-sensitive adhesives made from copolymers consist of vinyl acetate, vinyl laurate and waxes.

For hotmelt pressure-sensitive adhesives made from ethylene-vinyl acetate copolymers were produced with a relatively high proportion of chlorinated hydrocarbons, poor adhesive properties were achieved, so that the adhesives were mainly used as carpet underlays to make the carpets non-slip.

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So far it has been an unsolved problem with the components of hot melt pressure sensitive adhesives to be coordinated so that they have good UV and oxidation resistance, colorlessness or full transparency and show a low melt viscosity. Apparently, improvement in one property caused deterioration the other properties. Due to the targeted selection of the components, the present invention has succeeded in to create a hotmelt pressure sensitive adhesive which is satisfactory in every respect. The hot melt pressure sensitive adhesive according to the invention consists of a mixture of

a) polyacrylic acid and / or its derivatives and / or polyacrylic acid copolymers

b) modified or unmodified rosin, coumarone-indene resins, polyterpene resins, aliphatic diene-olefin hydrocarbon resins or polyterpene resins and

c) optionally a rubbery resinous block copolymer of styrene and butadiene or styrene and isoprener

Particularly suitable polyacrylic acid derivatives are polybutyl acrylates, Polymethyl methacrylate, polyethylene methacrylate and polyisobutyl acrylate

The mixture preferably contains the polyacrylic acid and / or its derivatives and / or the polyacrylic acid copolymer in a proportion of 5-70% by weight, preferably 25-50% by weight.

Component b), namely modified or unmodified rosin, coumarone-indene resins, polyterpene resins ^ iafiphatic Diene olefin hydrocarbons' '' ii in an amount of 5-80% by weight, preferably 20-40% by weight in the Mixture be present.

709808/0998

Dipl.-Ing. H.-J. Müfler P 25

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D TmUUThen so K0RE3 HOLDING ZUG AG - 3570

IjMUe-Grahn-Str. 38, TeL 475155

If necessary, the hotmelt pressure-sensitive adhesive according to the invention a block polymer of styrene and butadiene or styrene and isoprene in an amount of 5-60 wt. #, preferably 10 45 Weight # added.

The polyacrylates, their derivatives and polyacrylate copolymers in conjunction with component b) and optionally c) are distinguished by satisfactory adhesive properties and have the advantage over the known additives to hotmelt PSAs that they are much more stable. The molecular weight of component a) can vary within wide limits, it is preferably between 1,000 and 200,000. Depending on the composition the mix will work within these limits. Another advantage of the polyacrylates or their derivatives and polyacrylate copolymers in connection with component b) and optionally c) is in the low melt viscosity, so that the hotmelt pressure-sensitive adhesives according to the invention during handling and production, in particular also when applied to the Bring a simplification of the carrier film compared to the known ones. This is the case, for example, with the copolymers of ethylene and hotmelt pressure-sensitive adhesives containing vinyl acetate, premixes with part of the ethylene-vinyl acetate copolymer and the other components to form a meltable premix.

The hotmelt pressure-sensitive adhesives according to the invention can be produced by homogenizing, preferably by kneading, the components at a temperature of 80-160.degree. The relatively low viscosity of 10-10 cp / 160 ^° C. allows the adhesive to be applied to the carrier in a thin application.

However, a premix of the acrylate with the block polymer can also be used of styrene and butadiene or styrene and isoprene at a slightly lower temperature, since the acrylates have a : have dedigen melting point and then the rest Mix in components. This improves the heat transfer during the mixing process. Suitable for component b) rosin glycerol ester, rosin pentaerythritol ester or methylated or hydrogenated colophony esters, furthermore colophony polyethylene glycol esters and rosin ethylene glycol ester.

709808/0938

The polyterpene resins used are solid or liquid poly (alpha) Pinene and poly (beta) pinene with molecular weights from 100 to about 1300. The diene-olefin hydrocarbons have a molecular weight of 700-1500.

As block mixed polymers of styrene and butadiene or styrene and isoprene are used whose polystyrene groups have a molecular weight of 5000 - 130,000 and whose polybutadiene or Polyisoprene groups have a molecular weight between 16,000 and 300,000.

The present invention will now be based on exemplary embodiments are explained in more detail.

Example 1:

A mixture of

Polyisoprene-polystyrene copolymer 10 parts by weight polyvinyl ether 15 ""

Polypropylene polyacrylic acid ester

mixed poymerisat 30 ""

Coumarone-indene resin 34 ^wn

Stretching oil 10 ««

Antioxidant (blocked

Phenol) 0.5 "»

Homogenized at a temperature of 105 ° C. The homogeneous mixture is applied to a carrier film by means of a nozzle unit made of cellophane in a layer thickness of 20 g per cm2.

709808 / 099g

Aging tests showed that adhesive tapes produced in this way had excellent resistance to oxidation and UV. the Peel strength was 0.8 kg / 25 mm.

Example 2:

In a kneader a mixture of polyisoprene Polystyrolmischpolymerisat 2.5 weight was ₀ parts polypropylene Polyacrylsäureestermisch-

polyamine 41.5 ^MM

Polyterpene Resin 25.0 " ^M

Extending Oil 30.0 »»

Antioxidant (blocked

Phenol) 1.0 »"

homogenized at a temperature of 120 C. The homogeneous The mixture was applied to a carrier film made of polyvinyl chloride in a layer thickness of 20 g / cm2. The so produced Adhesive tapes showed a peel strength of 0.8kg / 25mm,

Example 3:

A mixture of poly-butadiene-polystyrene copolymer 30.0 parts by weight was used in a kneader Polypropylene-polyacrylic acid ester mixture

polymer 10.0 ^M "

Coumarone-indene resin '17.0 ^{w M}

.08.

709808/0998

Polyterpene resin 13.5 parts by weight

Extending Oil 18.5 ""

Antioxidant (blocked

Phenol) 0.5 ""

homogenized at a temperature of 120 ° C. The homogeneous mixture was applied to a paper support. Similar to in the previous examples, the peel strength values were excellent achieved. In particular, the adhesive tapes obtained showed hardly any signs of aging under extreme conditions.

Example 4;

Polyisoprene-polystyrene copolymer 12 parts by weight

Polyvinyl ether 18 ""

Polyacrylate 37 ""

Coumarone-Indene Resin 38.5 ""

Stretching oil 12 »"

Antioxidant (blocked

Phenol). 1 " "

homogenized at 100 ⁰ C. The adhesive tapes produced with this mixture were also characterized by high UV and oxidation resistance and good mechanical properties.

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Claims (6)

PATENT CLAIMS Transparent hotmelt pressure-sensitive adhesive with improved aging resistance, characterized by a mixture of a) polyacrylic acid and / or its derivatives and / or polyacrylic acid copolymers, b) modified or unmodified rosin, coumarone-indene resins, Polyterpene resins or aliphatic diene-olefin hydrocarbon resins and optionally styrene resins and c) optionally a rubbery resinous block copolymer of styrene and butadiene or styrene and isoprene. 2. Hotmelt pressure-sensitive adhesive according to claim 1, characterized in that the mixture as a polyacrylic acid derivative is a polybutyl acrylate, Contains polymethyl methacrylate or polyisobutyl acrylate. 3. Hotmelt pressure-sensitive adhesive according to claim 1 or 2, characterized in that the mixture contains 5-70% by weight , preferably 25-50% by weight, of polyacrylic acid and / or its derivatives and / or polyacrylic acid copolymers. . 4. melt pressure sensitive adhesive according to one or more of claims 1-3, characterized in that the mixture is 5-80% by weight, preferably 20 - 40% by weight of modified or unmodified rosin, Gumaron-indene resin, polyterpene resin or aliphatic diene. -Contains olefinic hydrocarbon resin. 709808/0998 5. hot melt pressure sensitive adhesive according to one or more of claims 1-4, characterized in that the mixture additionally contains 5 - contains 45% by weight block polymer of styrene and butadiene or styrene and isoprene - 60% by weight, preferably 10... 6. hot melt pressure sensitive adhesive according to one or more of claims 1-5, characterized in that the mixture as a polyacrylic acid copolymer, Polyolefin-acrylic acid copolymer and / or vinyl isobutyl ether-acrylic acid copolymer. 709808/0998